The Biden Administration purchased 600 million additional vaccines from Pfizer and Moderna through the end of July 2021. The speed at which vaccinations occur from then depend on how quickly they are manufactured, delivered, and administered. If all of these can happen quickly, it is possible that every American adult can be vaccinated by summer, but this can only happen with the cooperation of American citizens and quick and efficient work from the state distribution processes.
Since the emergence of the coronavirus, scientists have estimated that at least 70% to 90% of people must have immunity in order to achieve herd immunity; as of now, that number hasn’t changed. With current vaccination statistics at 48 million people, making only about 14.7% of the US population vaccinated, the prospect of herd immunity is low.
The uncertainty of whether the vaccines prevent transmission is a big concern because this is the key to herd immunity; if the virus cannot be transmitted to a host it cannot spread. Without knowing if the vaccines halt the transmission, we have no idea if this will continue to contribute to the spread. Because this type of spread comes from those who are vaccinated or are simply just carriers, it makes it that much more difficult to trace the origin of the virus and control the spread.
Vaccine roll-out campaigns continue to be uneven, contributing to the spread as well. Globally the disparities are high: Israel is about to breach the 70% threshold of vaccinations, while places like the states have hardly brushed 20%. Extreme cases like South Africa, have not even reached 10%; most data also do not include underdeveloped countries or countries who have not even had 1% vaccinations like Lebanon or Syria. Disparities like this cause more surges and opportunities for variants to emerge.
Other factors lowering the likelihood of herd immunity are attributed to vaccine hesitancy, emerging variants, and delayed arrival of vaccinations for children. With such a high rate of immunizations needed to meet herd immunity and due to the factors slowing down immunizations, surges and variants are still likely and the eradication of COVID globally becomes more unlikely.
Human behavior after being vaccinated is also a concern, especially when coupled with the uncertainty of virus transmission even if vaccinated. Those who have completed their vaccinations return to behaving as they did pre-COVID: lowering their usual protective habits and increase their interactions with others. Because the vaccines do not provide 100% immunity, it is still possible to contract COVID and spread it that way, thus having the same effect as being unvaccinated in terms of herd immunity.
As scientists begin to look more long-term, COVID-19 seems to be inching closer to becoming an endemic disease like the flu. Due to the increased protective habits to combat COVID we saw a decrease in flu cases, thus proving that behavior also affects transmission of diseases.
At this point, it will be almost impossible to stop the spread, so instead it is best to learn how to live with it as its effects wane over time.